Best available copx



July 24, 1923. 1,678,437

G. H. LELAND SHORT CIRCUITING DEVICE FOR MOTORS Filed April 16, 1925 Fig.1? Fig.5; Figlfl. Figll- 2 39.121.

//v VENTOR GEORGE H. LELAND.-

ATTORNEY [iii Patented July 24, 1928.

UNITED STATES 1,678,437 PATENT OFFICE.

GEORGE H. LELAND, OF DAYTON, OHIO, ASSIGNOR OF ONE-HALF TO THE LELAND ELECTRIC COMPANY, OF DAYTON, OHIO, A CORPORATION OF OHIO.

v SHORT-CIRCUITING DEVICE FOR MOTORS.

This invention relates to short circuiting devices for motors. Electric motors of the type known as repulsion induction motors are started as repulsion motors and after they have attained a predetermined speed are automaticallysconverted into induction motors. This is --usually accomplished by providing a short circuiting element .for the commutator bars'comprising a series of contact members or weights "adapted to be moved by centrifugal force into short circuiting contact With the commutator bars, a yieldable member acting on the contact weights to resist their outward movement and to retract the same into inoperative positions'when the speed-0f the motor is reduced below a predetermined point.

One object ofthe present invention is to provide a short circuiting device of this character whichwill be simple in construction, highlyelficient in operation and which can-be produced at a relatively low cost.

A further objectof the invention is to provide a short circuiting device of this character in which the contact weights will be retained in their proper relative positions and will be caused to move in unison.

A further object of the invention is to provide a short circuiting device of this character in which the contact weights will have butt contact with'the commutator bars but in which the contact will be broken in such a manner as to prevent injury to the contact surfaces by burning.

Other objects of the invention will appear as the device is described in detail.

In the accompanyingdrawings Fig. 1 is an end elevation, partly broken away, of a short circuiting device embodying my invention; Fig. 2 is alongitudinal sectional view taken centrally of a short circuiting device embodying my invention and of the commutator; Figs. 3 to 7 inclusive are detail views showing the relation of the contact portions of the weights to the commutator bars; Fig. 8 is an edge view of one of the dividing weights; Fig. 9 is a face view of the same; Fig. 10 is a face view of one of the loose weights; Fig. 11 isan edge view of one of the loose weights; and Fig. 12 is a detail view of the connecting ring.

In these drawings I have illustrated one embodiment of my invention and have shown the same in connection with a commutator comprising a body portion 1 rigidly mounted on an armature shaft 2 and having the usual circumferentialseries of contact bars 3 which are insulated one from the other and from the body 1--of-the-commu tator. I have not shown the motor as a whole nor the wiringfor the commutator as these are not necessary to an understanding of the, invention. 7 Arranged circumferentially of the shaft 2 is a short circuiting element comprising an annular series of contact members or weights which areadapted to be moved by centrifugal .force into short circurtmg contact with the commutator bars 3; In the present construction these contact weights are of two kinds, the-weights 4 being loosely mounted and the weights 5 be mg connected one with the other, as will be hereinafter explained. This series of contact weights are confined between the for ward face of the commutator, that is, the face remote from the motor, and a plate or disk 6, which is mounted on-the shaft 2, and which may, if desired, have both rotatory and axial movement with relation thereto, but the axial movement of which, away from the commutator, is limited by a stop, such as a split ring 7 mounted in a g'roove 8 III the shaft 2. Cooperating with the contact weights is a yieldable member which serves to resist the outward movement of the weights and to retract the same into inopera two positions when the centrifugal force which has moved them outward is dicontinued. In the present arrangement this yiedable member also serves to press the contact portions of the weights firmly'in engagement with the face of the commutator and to hold the weights against lateral displacement, that is, displacement lengthwise of the shaft 2. To this end each of the weights has its outer end shaped to provide a shallow recess as shown at 8 the bottom or lowest radial part of which is purposely located in closer proximity to the plate 6 than to the commutator 1. The yieldable member, preferably a helical coil spring 17 tending to seek the bottom or lowest radial part of this recess, engages the plate 6 holding it yieldingly against the lock ring 7 and its reaction upon the contact members holds them in similar frictional contact with the face of the commutator. Consequently the yieldable band not only serves to resist the outward movement of the weights and to retract the same but it also serves the additional purpose V of maintaining 1a constant frictional contact between tlie wig hts and the commutator, between the band a.nd the disk, and between the di andthe lock ring.

These various fricftioiiallengageroents 'calnfberegulated in' production varying the shape of the outer ends of -the;eveigll tizi they always serve to insure smooth operation as nothing is left loose to rattle or chatter,-while uniform wear of the parts 1s attained by the faoti that the devicewotates slightly with respect to the commutator as:

the motor starts =an'd'stops, "Due tof-the fact that the yieldable band is of an elastic characterthere is-very little relative movement of theband. with relation 'td the Wei'ghts-an'd the frictional contact-between the weights and theband-jis' reduoed=to afimijnir'num;

"The several Weights 4' ma "5 are provided on *their' rear edgesy that -is',; the' ed e nd:

j acent to the face ofthe oommumwa with projections and- 10" whicht bear 'againstfthe face of the commutator nflid -forin" t-he'--solef points of contact between the i weights and the commutator, thosserving to minimize the frictionbetween these-parts? The pro stitutesthe contact portion of-fhe' weight,

I which engages the commutatorbarf and this contact port1on=or pro ect1on' 9 'andthe commutator. bars are shaped and ar r-anged with relation one to' the fother that the weights will engage thebafis with-abutting contact but-- there will be nosparkingbe'tween the main contact surfaces when -the weights move away from thebars, whicli' wou ld tend to burn the surfaces and preven't'the proper tions of the bars and which are here shown as arcs of substantially ninety degrees The cont-actportion or projection 9 of each weight has its outer edge curved to-conforin to the curvature of the. recess or seat in the commutator 'bars. Preferal'ily the contact edge of the weight'is describedabout axis so arranged that when this edge is "in engagement with the commutator bar: the center will be substantially in longitudinal alinement with theinner edge ofthe cornmutator bar and in substantially radial alinement with the forward end of that bar. Inasmuch as the curved-recess in the commutator bars conforms to the'curva-turc of the edge of the weight it willbei obvious that this are is described about this same center. lVhcn the contact weight is inits outer position it will be in full-contact with one or moreof the commutator bars through cction' at the outei cn'd-of eachweightcon said circle, all'portions of the contact surface of the weight; will simultaneously more out of engagement with the commutator bar .hiztrtheioutei wrtion of the contact surface of the weight will move away from the adjaccnt'g'iortion of the bar more rapidly than will the inner portion of that contact surface, as'will'be apparent. from an examination-of Figs-3 to 7. 1 Any tendency of the current to-bridge =the gap between the-two contact surfaces, =as they separate, will naturally take place atthepointwhferethe distance between the-members istheshortest, that is, at. the

lower portxonsof the contact surfaces, and

any burningwhich ,may result from this sparking will xbe'confined to these portions of ,the contact-surfaces andthe major portiousof those surfaces will notibeburned but willalways be in acondition to effecta per feet electrical contact. 7

NV hen the short circuiting elemcnt'consist's of loose weights, such as are shown at 4,, there .15 sometimes a= tendency --for these weightsto .move outwardly at different times-due to variations in frictional rcsistence, or to other -causes,.- and, further, the

spacing-between'the weights when they are inth'eir. outermostipositions is sufficient to. permit one or -more of the weights to get out.

of-its proper positionavith.relation to the other weightsandtherebyi-cause the weights to pile up onto interlock ,in such a-manner as to prevent-proper retraction thereof. the construction here weights 4 are divided into substantially equal groups by the dividing weights 5 which, as has been above explained, are connected one to the other so as to cause them;

to move in unison. In that form illustrated each of the dividing weights comprises a relatively tlat radially extending portion of a width substantially equal to the width of the loose weights. The inner portion of this weight is bent laterally and extends about the circumference of the shaft 2 for a distance of approximately ninety degrees, as shown at 12, the loose weights having their forward edges cutaway at the inner ends, thereof to form ,a recess 13 In which these,

laterally extending portions of the dividing weights are arranged. Any suit-able number of dividing weights may be employed but, as here shown, there are six of these dividing weights and consequently the laterally extending portions thereof overlap and the overlappingportions are so shaped as to prevent them coming in contact one with the other. -Loosely mounted on the shaft 2 is a connecting member with which the ends of the laterally extending portions shown the looseof the dividing weights are pivotally connected. In the present construction this connecting member comprises a flat ring 14 which is mounted on the shaft 2 for rotatory movement with relation thereto and it is provided in its inner periphery with a series of notches 15 adapted to receive lugs 16 extending laterally from the inner ends of the inner-portions 12 of the dividing weights. The arrangement of the lugs within the notches is such that the inner ends of the weights will have no appreciable radial or circumferential movement with relation to the ring but will-have free pivotal movement in the notches. When one of the dividing weights 5 tends to move outwardly, due to centrifugal force, .its outer portion will-move. in. a substantially radial directionan'd inorder to permit of this movement theinner end of that weight must be laterally displaced with relation to the shaft. 'lhe -inner ends of the severaldividing weightsbeing connected one with the other it will :be obvious thatfthe lateral displacement ofthe inner end of one weight will cause the like displacement of the inner ends of all dividing weights and these weights will be caused .to. move in unison. Further, inasmuch aseone of thedividing weights cannot move-independently of the others it necessarily follows :that none of the weights will-.move.outwardly until the centrifugal force is sufficient to move all of them outwardly. The dividing weights separate the loose weights into relatively small groups and the space between the loose weights of each group when they are in their outermost positions, is not sufficient to permit of the displacement of one weight with relation to the other.

' \Vh'ile I have shown and described one embodiment of my invention I wish it to be understood that I do not desire to be limited to the details thereof as various modifications may occur to a person skilled in the art.

Having now fully described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In adevice of the character described, the combination with a shaft, and a comi'uutator mounted on said shaft and comprising a series of bars, of an annular series of substantially radial contact members arranged circumferentially of said shaft and movable in substantially straight lines by cci'itrifugal force into short circuiting contact with said commutator bars, means for connecting the inner ends of a part of said contact members one to the other to cause them to move in unison, and a yieldable device acting on said contact members to resist their outward movement.

2. In a device of the character described.

' the combination with a shaft, and a com- [act with said commutator bars,a part of said contact members having portions extending inwardly and laterally with relation to the other contact members, means for connecting the inner ends of the first mentioncd contact members one to the other to.

cause said contact members to act in unison, and a yieldable device acting on all. of said contact members to resist their outward movement. a v i 8. In a device of the character described, the combination with a shaft, and a commutator mounted on said shaft and comprising a series of bars, of an annular series, of con-v tact members arranged circumferentially of said shaft and movablebycentrifugal force into short circuiting contact-withsaid commutator bars, a member mounted on said shaft for rotatory movement, and means for so connecting a part of said contact members with said rotatable member that said part of said contact members will be caused to move outwardly in unison,said part of said contact members being arranged to divide the other contact members into groups, and a yieldable device acting on all of said contact members to resist their outward movement.

4-. In a device of the character described, the combination with a shaft, and a commutator mounted on said shaft and comprising a. series of bars, of an annular series of contact members arranged circumferentially of said shaft and movable by centrifugal force into short cireuiting contact with said commutator bars, a part of said contact mem-' bers having port-ions extending inwardly beyond the adjacent portions'of the other contact members and about said shaft, and a member mounted on said shaft for rotatory movement with relation thereto and connected with said inner portions of said contact members to cause the latter to move in unison, and a yieldable device acting on all of said contact members to resist their outward movement.

5. In a. device-of the character described,-

her, the last mentioned contact members being arranged to divide the other contact members into groups, and a yieldable device acting on said contact members to resist their outward movement.

6. In a device of the character described, the combination with a shaft, anda commutatormounted on said shaft and comprising a series of bars, of an annular series of contact 'n'iembers' arranged circumferentially of said-shaft and movable by centrifugal force. into short circuitin contact with said commutator bars, a ring ooselymounted on said shaft and having recesses therein, a part ofsaid contact members havinginner portions extending circumferentially of said shaft and provided at their ends with parts extendinginto the respective recesses in said ring-to pivotally connect said Weights with said ring, and a yielda-ble member. acting on all of said contact membersto resist:

theiroutward movement, V

7. Ina device of'the character described, the combination with a shaft, and a commutator mounted on said shaft and comprising a series of bars,-of an' annular series of contact members arranged circumferentially of said shaft and 'movable by centrifugal force into short circuiti-ng contact with said commutator bars, the several contact: mem-- bers having portions of their inner ends cut away toprovide an annular recess extending about said shaft, a part-of'said contact'mem bers having inner portions arranged in said annular recess and extending circumferenti'ally-ofsaid shaft, a connecting member mounted I on :said shaft for rotatory movement with relation thereto, said-inner portions of said'part of said contactmembers being .pivotally connected with said connecting member, ands; yieldabledevice acting'on the several weights to resist their outward movement. I

8. In-a device of the character described, the combination with a-shaft, and a commutator mounted on said shaft and comprising a series of bars, of a plurality of groups of contact members arranged circumferentially of said shaft for movement by centrifugal force into short circuiting contact with said commutator bars, other members having parts arranged between the respecti-ve groups of said contact members and movable outwardly by centrifugal force and also having laterally extending inner portions arranged circumferentially of said shaft, a device supported on said shaft for rotatory movement-relatively thereto and having pivotal connection with the inner portions of the last mentioned members to cause them to moveoutwardly in unison, and a yieldable device acting on all of said members to resist their outward movement.

9. In a device of the character dercribed, the combination with a shaft, and a commutator mounted. on said shaft and comprising a series of bars, of a disk mounted on saidshaft and spaced from the face of said commutator, an annular series of contact members mounted in the space between said disk and said commutator for radial movement by centrifugal force into short circuiting contact with said commutator bars, each of said-contact members having a curved recessin its-outer end,- said recess sloping from said commutator toward said disk, and a contractileaband encircling said contact members and engaging the 'rece-scd ends thereof andsaid disk to resist the outward mQVement-Qfsaid contact members and to press the same against said commutaton.

3'10. In a'device of the characterdescribed, a shaft, :1 commutator mounted on said shaft and comprising bars, the ends of which overhang the faceof said commutator, the overhanging portions of said ba'rs having their inner tcorners cut away to form arcuate recessesaa seriesof weight-s arranged cir' cumferentially of said-shaftfor movement in substantially straight-lines by centrifugal force into short circuiting contact with said commutatornbars, said weights having contact: portions in sliding contact with the face of said-commutator and curved to conform to the contour of the arcuate recesses in said commutator bars, and a yieldable device acting on said weights to resist their outward movement and to ress said contact portions thereof against said commutator.

11. Ina-device of the-character described, a shaft, a commutator mounted on said shaft and comprising bars, the ends of which overhang the face of said commutator, a series ofWei-ghts arranged circumfcrentially of said shaft and in sliding contact with the face of said commutator and movable by centrifugal force into short circuiting contact with said commutator bars, each of said weights having a contact portion the edge of which conforms to the arc of a circle described about a center spaced substantially equal distances from the outer end of said weight and from that edge of said weight which is adjacent to said commutator, the overhanging ends of said commutator bars having their inner corners cut away to form arcuate recesses which conform to the shape of the contact portions of said weights, and a yieldable device acting on said weights to resist their out-ward movement and to press said contact portions thereof against the face of said commutator.

12. In a device 'of the character described, ashaft, a commutator mounted on said shaft and comprising commutator bars, said bars being so constructed as to present acurved contact surface, a series of weights arranged circumferentially of said shaft and arranged to be moved in substantially straight lines under centrifugal influence into short circuiting contact with said bars, each of said weights being provided with a curved contact surface the curvature of which conforms to the curved contact surface of the bars, the weights and the commutator bars being respectively so proportioned with respect to their opposed contact surfaces that as the weights move outwardly they effect substantially full faced engagement as short circuiting contact occurs.

13. In a device of the character described, a shaft, a commutator mounted on said shaft and comprising commutator bars, said bars being so constructed as to present a curved contact surface, a series of weights arranged circumferentiall of said shaft and arranged to be moved und er centrifugal influence into short circuiting contact with said bars, each of said weights being provided with a curved contact surface the curvature of which conforms to the curved contact surface of the bars, the weights and the commutator bars being respectively so proportioned that as the weights move outwardly toward the commutator bars the opposed curved surfaces of the weights and the bars will be in progressively varying diverging relation until the instant of contact.

14. In a device of the character described, a shaft, a commutator mounted on said shaft and comprising commutator bars, said bars being so constructed as to present a curved contact surface, a series of weights arranged circumferentially of said shaft and arranged to be moved under centrifugal influence into short circuiting contact with said bars, each of said weights being provided with a curved contact surface the curvature of which conforms to the curved contact surface of the bars, the weights and the commutator bars being respectively so proportioned that as the Weights move outwardly toward the commutator bars the opposed curved surfaces of the weights and the bars will be in progressively varying diverging relation until the instant of contact, but will effect substantially full face engagement as short circuiting contact occurs.

In testimony whereof, I aflix my signature hereto.

GEORGE H. LELAND. 

